With the advent of the nano-technology, the need of nano-structures of atom-level precision is dramatically increased. Thus, a variety of nano-imprinting techniques are developed, such as micro-contact printing, scanning probe-based techniques and nano-imprint lithography. Among these techniques, the nano-imprint lithography allows for repeated printing with one single mold that is obtained with one single lithography step. The nano-imprint lithography is thus one of the most promising techniques for nano-imprinting, having the advantages of low cost and high yield with wild applications in for example nano-electronics, optic devices, high density storage devices, nano-electro-mechanical systems, bio-devices, transducers and nano-electromagnetic devices.
The factors that affect the development of the nano-imprinting lithography includes alignment between layers in a multi-layer imprinting process, yield and acceptable rate of products in large-scale molding, manufacturing of mold for high density patterns, low yield rate caused by work adherence to mold, control of temperature and pressure of mold imprinting and deformation and service life of the mold. Among these factors, deformation of mold plays a key role in determining the quality of the nano-scale products. Once the deformation of mold exceeds an acceptable level, the nano-structure printed loses uniformity, leading to poor quality of the associated products. This is particular of concern in high speed imprinting process that makes a great number of imprinting products in a short time. Thus, the deformation of the mold must be monitored from time to time to ensure high quality products. The deformation that is of concern in nano-imprinting is of nano orders and thus real-time monitoring is necessary.
In nano-imprinting techniques, precision of molds is a key indication for quality of the imprinted products. Although theories of material mechanics and computers can be effectively used to establish micro-element model for the prediction of mold deformation, the difference between theoretical solution and practical applications always leads to unacceptable predictions of the practical influence caused by mold deformation. Further, the known techniques do not provide real-time monitoring scheme and cannot be employed in automation of nano-imprinting.